I found an explanation of his earlier behaviour. He had seemed distraught and ill at ease when he had joined Madame de Stämer, Miss Beverley, and myself in the drawing room. I could only suppose that this and the abrupt parting with me outside my door had been due to his holding a theory which he had proposed to put to the test before confiding it to me. I remember that I spoke very slowly as I asked him the question:
“Whose is the lighted window, Harley?”
“Has Colonel Menendez taken you into a little snuggery or smoke-room which faces his bedroom in the southeast corner of the house?”
“No, but Miss Beverley has mentioned the room.”
“Ah. Well, there is a light in that room, Knox.”
“Possibly the Colonel has not retired?”
“According to Madame de Stämer he went to bed several hours ago, you may remember.”
“True,” I murmured, fumbling for the significance of his words.
“The next point is this,” he resumed. “You saw Madame retire to her own room, which, as you know, is on the ground floor, and I have satisfied myself that the door communicating with the servants’ wing is locked.”
“I see. But to what is all this leading, Harley?”
“To a very curious fact, and the fact is this: The Colonel is not alone.”
I sat bolt upright.
“What?” I cried.
“Not so loud,” warned Harley.
“But, Harley”
“My dear fellow, we must face facts. I repeat, the Colonel is not alone.”
“Why do you say so?”
